Catheter reinforcing braids

ABSTRACT

An intravascular catheter having an elongated tubular body with a proximal portion, a distal portion and a lumen extending therebetween. The tubular body is formed with polymeric materials, preferably containing no radiopaque filler, and metallic reinforcing braiding configured to provide the catheter with radiopaque properties and/or kink resistance.

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/645,381, filed May 13, 1996 now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to intravascular catheters, and moreparticularly to a catheter having metallic reinforcing braidingconfigured to provide the catheter with radiopaque properties and/orkink resistance.

Several types of catheters are utilized for intravascular treatment.Examples of intravascular catheters include guide catheters, angioplastycatheters, stent delivery devices, angiographic catheters, neurocatheters, and the like.

Guiding catheters are commonly used during coronary angioplastyprocedures to aid in delivering a balloon catheter or otherinterventional medical devices to a treatment site in a coronary vessel.In a routine coronary angioplasty procedure, a guiding catheter isintroduced into a peripheral artery and advanced over a guidewirethrough the aorta until the distal end of the guiding catheter isengaged with the appropriate coronary ostium. Next a balloon dilatationcatheter is introduced over the guidewire and through the guidingcatheter. The guidewire is advanced past the distal end of the guidingcatheter within the lumen of the diseased vessel and manipulated acrossthe region of the stenosis. The balloon dilatation catheter is thenadvanced past the distal end of the guiding catheter over the guidewireuntil the balloon is positioned across the stenotic lesion. After theballoon is inflated to dilate the blood vessel in the region of thestenotic lesion, the guidewire, balloon dilatation catheter and guidingcatheter are withdrawn.

Guiding catheters typically have preformed bends formed along theirdistal portion to facilitate placement of the distal end of the guidingcatheter into the ostium of a particular coronary artery of a patient.In order to function efficiently, guiding catheters should have arelatively stiff main body portion and soft distal tip. The stiff mainbody portion gives the guiding catheter sufficient "pushability" and"torqueability" to allow the guiding catheter to be insertedpercutaneously into a peripheral artery, moved and rotated in thevasculature to position the distal end of the catheter at the desiredsite adjacent to a particular coronary artery. However, the distalportion should have sufficient flexibility so that it can track over aguidewire and be maneuvered through a tortuous path to the treatmentsite. In addition, a soft distal tip at the very distal end of thecatheter should be used to minimize the risk of causing trauma to ablood vessel while the guiding catheter is being moved through thevasculature to the proper position. Such a soft tip is described in U.S.Pat. No. 4,531,943. In additon, the inner surface of the guidingcatheter should be lubricious to facilitate movement of guidewires,balloon catheters and other interventional medical devices therethrough.

Angiographic catheters can be used in evaluating the progress ofcoronary artery disease in patients. Angiography procedures are used toview the patency of selected blood vessels. In carrying out thisprocedure, a diagnostic catheter having a desired distal end curvatureconfiguration may be advanced over a guide wire through the vascularsystem of the patient until the distal end of the catheter is steeredinto the particular coronary artery to be examined.

A non-limiting example of an angioplasty catheter is found in U.S. Pat.No. 4,646,742. A non-limiting example of a stent deployment device isfound in U.S. Pat. No. 5,201,757.

In that the path taken by intravascular catheters is sometimes tortuous,it is important that an intravascular catheter can be steered bytorquing its proximal hub and that the torque be transmitted to thedistal end in a smooth, controllable fashion. Moreover, the cathetershould have sufficient strength in the longitudinal direction so as notto kink or fold as it is advanced through the vascular system. It shouldalso possess a lubricious core lumen to facilitate passage of aguidewire or possibly another catheter or device therethrough.

It is also a desirable feature of certain intravascular catheters thatit possess a relatively large lumen to allow fluids, such as radiopaquecontrast fluid to be injected therethrough and out the distal end sothat the area of the vascular system under investigation can be viewedfluoroscopically.

It is also a desirable feature of certain intravascular catheters thatit possess radiopaque and/or kink resistance qualities.

The desirable properties of a catheter having a relatively small O.D.and a relatively large I.D. dictates a relatively thin wall. To maintainthe desired torqueability and pushability characteristics of a thin wallcatheter calls for considerable ingenuity in the formulation of thematerials employed and the constructional techniques utilized.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided anintravascular catheter with an elongated tubular body having a proximalportion, a distal portion and a lumen extending therebetween. Thetubular body has a first layer defining the lumen, the first layer madeof a polymer having a coefficient of friction of less than about 0.50; asecond layer disposed about the first layer, the second layer made of apolymer selected from polyetherester elastomer, polybutyleneterephthalate, and combinations thereof; and a reinforcing means. Thefirst layer may be a polymer selected from polytetrafluoroethylene,polyvinylidene fluoride, and polyamide, and may be a polymer having akinetic coefficient of friction (steel on polymer) less than about 0.35,and preferably less than about 0.10. The first layer may consistessentially of polytetrafluoroethylene. The second layer may have adurometer of from about 30D -90D, and may be from about 38D -74D. In oneembodiment, the second layer will preferably be about 30D at the distalend of the bodystock and about 90D at the proximal end of the bodystock.The second layer may be polyetherester blended with polybutyleneterephthalate such as about 10-94 weight percent polybutyleneterephthalate. The second layer may be about 8-12 weight percentpolyetherester and about 88-92 weight percent polybutyleneterephthalate. The reinforcing means may be totally embedded between thefirst layer and the second layer, or substantially embedded in thesecond layer. The reinforcing means may be a braided metal mesh offilaments extending from the proximal portion of the tubular body towardthe distal portion of the tubular body by a predetermined distance. Thereinforcing means may extend to the distal portion of the catheter. Thebraided metal mesh may be metal filaments braided in a 1 over 1 patternor 2 over 2 configuration, and may be made of filaments formed of ametal selected from stainless steel and ELGILOY nickel-cobalt alloy. Thereinforcing means may be a polymer forming a mesh, a tube, or a fabric,and the polymer may be carbon fibers or polyaramide. The intravascularcatheter may have an annular soft-tip member bonded to the distal end ofthe tubular body member, and the soft-tip member may be polyetheresterelastomer having a durometer less than about 50D. The intravascularcatheter may have an outer diameter in the range of from about 2 Frenchto 24 French, preferably from about 4 French to about 12 French.

In another embodiment of the present invention, the present inventionrelates to a guide catheter having an elongate tubular body with aproximal portion, a distal portion and a lumen extending therebetween.The tubular body has an outside diameter of from about 4 French to about12 French and has a first layer forming the lumen and made ofpolytetrafluoroethylene; a braided metal mesh of filaments at leastpartially surrounding the inner layer; and a second layer at leastpartially covering the reinforcing means, the second layer made of ablend of polyetherester elastomer and polybutylene terephthalate. Thesecond layer may have a durometer of from about 38D -74D, and may bemade of about 10-94 weight percent polybutylene terephthalate. In oneembodiment, the second layer will preferably be about 30D at the distalend of the bodystock and about 90D at the proximal end of the bodystock.The second layer will preferably be made of about 8-12 weight percentpolyetherester and about 88-92 weight percent polybutyleneterephthalate. The braided metal mesh may be made of metal filamentsbraided in a 1 over 1 pattern or 2 over 2 configuration. Theintravascular catheter may further include an annular soft-tip memberbonded to the distal end of the tubular body member, and the soft-tipmember may comprise polyetherester elastomer having a durometer lessthan about 50D.

In another embodiment of the present invention, the present inventionrelates to an intravascular catheter having an elongate tubular bodyhaving a proximal portion, a distal portion and a lumen extendingtherebetween. The tubular body may be made of: (a) polymeric materialcontaining substantially no radiopaque filler; and (b) metallicreinforcing braiding configured with sufficient effective thickness toprovide the elongate tubular body with substantial radiopacity. Thepolymeric material may be a polymer selected from polyetheresterelastomer, polybutylene terephthalate, and combinations thereof. Themetallic reinforcing braiding may be configured in a one-over-one pairedwire construction.

In yet another embodiment of the present invention, an intravascularcatheter has an elongate tubular body with a proximal portion, a distalportion and a lumen extending therebetween, and the tubular body is madeof: (a) polymeric material containing substantially no radiopaquefiller; and (b) metallic reinforcing braiding, wherein the combinationof polymeric material comprising substantially no radiopaque filler andmetallic braid has an amount of radiopacity which is greater than orequal to the amount of radiopacity which would result from a catheterwithout metallic reinforcing consisting of polymeric material loadedwith 20% barium sulfate, preferably greater than about 30%, morepreferably between about 30-40%.

DESCRIPTION OF THE DRAWINGS

The foregoing features, objects and advantages of the invention willbecome apparent to those skilled in the art from the following detaileddescription of certain preferred embodiments especially when consideredin conjunction with the accompanying drawings in which like numerals inthe several views refer to corresponding parts. These figures areprovided to illustrate, and not limit, the present invention.

FIG. 1 is a plan view of one embodiment of the guiding catheter of thisinvention with a portion of the catheter removed to show theconstruction of the bodystock;

FIG. 2 is a longitudinal sectional view of the distal portion of oneembodiment of the guiding catheter of this invention prior to theattachment of the stem and tip;

FIG. 3 is a longitudinal sectional view of the stem transition sleeveand stem sleeve prior to assembly of the guiding catheter of thisinvention;

FIG. 4 is a longitudinal sectional view of the distal portion of oneembodiment of the guiding catheter of this invention;

FIG. 5 is a plan view of the distal portion of the guiding catheter ofthis invention showing the stem transition sleeve, stem sleeve and softtip;

FIG. 6 is a perspective view of a diagnostic catheter constructed inaccordance with the present invention;

FIG. 7 is a cross-sectional view of the catheter of FIG. 6 taken alongthe line 2--2;

FIG. 8 is a cross-sectional view taken through the stem member of thecatheter along the line 3--3 in FIG. 6;

FIG. 9 is a longitudinal cross-sectional view taken along the line 4--4which passes through the joint between the tubular body stock and thestem member;

FIG. 10 is a longitudinal cross-sectional view taken through the distalend portion of the catheter along the line 5--5 in FIG. 6;

FIG. 11 is a plan view of an additional embodiment of the presentinvention;

FIGS. 12 and 13 show alternative embodiments of metallic reinforcingbraiding in accordance with the present invention;

FIG. 14 shows alternative angles of braiding according to the presentinvention; and

FIG. 15 shows a cross-section of a catheter in accordance with thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment of the invention is a guiding catheter 10 which has atubular bodystock 20 and a soft tip 30 attached to the distal end ofbodystock 20. Guiding catheter 10 can have any desired inner diameterand outer diameter. Typical dimensions are an inner diameter of betweenabout 0.050 inches to about 0.130 inches (0.127 cm to 0.330 cm) and anouter diameter of about 0.070 inches to about 0.150 inches (0.178 cm to0.381 cm). A conventional polycarbonate hub 40 is attached to theproximal end of bodystock 20. In addition, an extruded strain relieftube 50 is connected to hub 40 and the proximal portion of bodystock 20.Strain relief tube 50 preferably may have a tapered design as shown inFIG. 1. However, a constant outside diameter construction could also beused.

Bodystock 20 is formed from an inner liner 21, an intermediate wire meshbraid 22 and an outer jacket 23. Inner liner 21 is formed from a polymerhaving a coefficient of friction of less than about 0.50, preferablypolytetrafluoroethylene. Suitable polytetrafluoroethylene can bepurchased on the open market. The polytetrafluoroethylene preferably hasa thickness of between about 0.0010 inches (0.0025 cm) and about 0.0050inches (0.0127 cm).

Inner liner 21 when formed from a polymer having a coefficient offriction of less than 0.50 provides a lubricious surface facing thelumen of guiding catheter 10. This facilitates the passage of othermedical devices therethrough.

Metallic reinforcing braid 22 is formed from, e.g., stainless steelwires disposed over inner liner 21. Although stainless steel wire ispreferred, other suitable materials such as ELGILOY nickel-cobalt alloycould also be used. The stainless steel wire may have a circularcross-section with a diameter of between about 0.0010 inches (0.0025 cm)and about 0.0050 inches (0.0127 cm), preferably about 0.003 inches(0.008 cm). Alternatively, a flat wire could be used. The metallicreinforcing braid 22 is described in more detail below.

Outer jacket 23 is formed from a blend of polyetherester elastomer andpolybutylene terephthalate (PBT). Suitable polyetherester elastomer andpolybutylene terephthalate (PBT) can be purchased on the open market.Outer jacket 23 may have a durometer of between about 38D and about 74D.In one embodiment, the second layer will preferably be about 30D at thedistal end of the bodystock and about 90D at the proximal end of thebodystock. The use of a polyetherester elastomer/PBT blend provides abodystock material that is sufficiently stiff so that guiding catheter10 has a proximal portion with enhanced "pushability" and"torqueability".

Preferably, the polymeric material for outer jacket 23 and inner liner21 will contain substantially no radiopaque fillers such as bariumsulfate, bismuth subcarbonate, bismuth trioxide and bismuth oxychloride.Preferably the outer jacket 23 and/or inner liner 21 will contain lessthan 5 weight percent radiopaque filler, more preferably less than 1weight percent, even more preferably less than 0.5 weight percent, andmost preferably 0 weight percent. A pigment can be used to color outerjacket 23. If such a pigment is used, preferably about 0.05 to about0.5% by weight is used. Lesser or greater amounts of the pigment can beused depending on the color desired.

Soft tip 30 constitutes the most distal end of guiding catheter 10. Itis formed from polyetherester elastomer. Preferably soft tip 30 has adurometer of between about 25D and about 50D. This gives soft tip 30 asoftness that is sufficient to minimize the chances of damage to theinner surface of a blood vessel through which a guiding catheter 10 maypass. In addition, it is hard enough to maintain an opening therethroughto allow the passage of a guidewire, balloon catheter or otherinterventional medical devices to pass out of the distal end of soft tip30. Soft tip 30 can be made radiopaque by mixing, e.g., 15-50% by weightbarium sulfate with the polyetherester elastomer. Of course greater orlesser amounts of barium sulfate or other radiopaque filler can be used.A 4% by weight loading of titanium dioxide can be used to color soft tip30. Again greater or lesser amounts of titanium dioxide can be used.Preferably soft tip 30 has a length of between about 0.04 inches (0.10cm) to about 0.20 (0.51 cm) inches.

Guiding catheter 10 may have a stem 80 located between bodystock 20 andsoft tip 30. Stem 80 is composed of stem transition sleeve 51 and a stemsleeve 52. Stem transition sleeve 51 is formed from 38D to 55Dpolyetherester elastomer. It will preferably contain no radiopaquefillers such as barium sulfate. Organic pigment can be used. Stem sleeve52 is formed from 38D to 55D polyetherester elastomer. It willpreferably contain no radiopaque fillers such as barium sulfate. 4% byweight of titanium dioxide or 0.4% by weight of an organic pigment canbe used to provide color to stem sleeve 52.

Stem transition sleeve 51 has a taper along the distal portion. Thistaper as shown is about 20 degrees but can generally be from about 0degrees to about 30 degrees. Stem sleeve 52 has a complementary taperalong its proximal portion to provide a smooth transition between stemtransition sleeve 51 and stem sleeve 52. The length of stem sleeve 52can vary depending on the length of the distal portion of guidingcatheter 10 that is desired to be flexible. Stem sleeve 52 may be fromabout 0.45 inches (1.14 cm) to about 2.1 inches (5.33 cm) as measuredfrom its most distal end to the most proximal end of the taper. Inaddition, stem 80 can have a total length of between about 0.5 inches(1.27 cm) to about 6 inches (15.24 cm).

Stem transition sleeve 51 and stem sleeve 52 fit over the distal portionof bodystock 20. This configuration provides a smooth transition in theflexibility of guiding catheter 10 from its proximal end to its distalend. This smooth transition from the high hardness/stiffness ofbodystock 20 to the high softness of soft tip 30 eliminates stressconcentration at the stem to bodystock joint. High stress concentrationsat this joint would promote kinking and failure of guiding catheter 10.

Guiding catheter 10 can be manufactured according to the followingprocess.

Step A

1. Clean a weld mandrel with alcohol and lint free cloth.

2. Slide mandrel 90% into an etched PTFE tube. Tie a knot about 1/2 inchfrom the end of the PTFE tube, and slide the weld mandrel the rest ofthe way into the PTFE. Trim excess PTFE outside of the knot.

3. Cut braided metal stock to a desired length. Slide the braid stockinto an assembly tube. Remove and dispose of the braid core rod whileholding the free end of the braid assembly with other hand. This leavesthe unsupported braid inside the assembly tube. Slide the end of thePTFE/mandrel assembly (knot end first) into the braid which is in theassembly tube. Remove the braid/PTFE/mandrel from the assembly tube.Snug and secure the braid down onto the PTFE by pulling it axially andtwisting the free ends. Trim the twisted braid back to about 1/4 inchbeyond the end of the weld mandrel on both ends.

4. Cut a desired number of outer layer tubes, such as a first, secondand third outer layer tubes, to desired lengths. Each tube may havedifferent durometers. Make one slit in each first and second tubeaxially along their length. Tube three is not slit. Slide the threetubes onto the braid/PTFE/mandrel assembly. Move the tubes togetheruntil each is butted against the adjoining tube, but not overlapped. Thethree tubes should be approximately centered on the braid/PTFE/mandrelassembly. Slide a piece of the assembly heat shrink completely over thetubes/braid PTFE/mandrel assembly, until it is also centered on thetubes/braid/PTFE/mandrel assembly. Using a hot air source at about 200°F. to 400° F., shrink the assembly heat shrink in four places: both endsand above both tube butt joints.

5. Place heat shrink/tubes/braid/PTFE/mandrel assembly in pre-heatedconvection oven at a desired temperature for a desired time and thenremove. The time shall begin when the oven temperature has recovered towithin 10° F. of the specified temperature. During this process andduring the subsequent cooldown after removal from the oven, nothing isto touch the assembly, except at the ends (where there are no tubes).

6. After the part has cooled to a comfortable touch, remove the heatshrink by slitting it axially over its length. Dispose of used heatshrink. Trim the twisted braid on one end of the assembly to expose theweld mandrel. Pull the weld mandrel out of the now fused tube/braid/PTFEassembly.

7. Trim both ends of the catheter to the specified length using a singleedge razor blade and specified trim mandrel.

Step B

1. Set a defined time and temperature of a tip welding system.

2. Cut the tip tubes to the desired length. Place one tip tube on thetip weld mandrel, and slide it against the step. Cut tip heat shrink toa desired length, and slide it onto the catheter. Gently place the tipweld mandrel/tip tube assembly into the catheter until the end of thecatheter butts against the tip tube, and then slide the heat shrink ontothis assembly until it overlaps the tip tube completely.

3. Ensuring that no relative motion occurs between the pieces of theweld mandrel/tip tube/catheter/heat shrink assembly, place it in theproper location between the jaws of the tip welding fixture. Axialorientation is correct when the right end of the tip welding mandrel isapproximately aligned with the right end of the jaws of the welder.Start the welding system when alignment is achieved.

4. When the welding cycle is complete and the part cool to the touch,remove the heat shrink. Push the catheter off from the mandrel bypushing against the distal end of the soft tip.

5. Visually inspect the catheter/soft tip weld area with a microscopefor defects.

6. Mount a trimming pin into a small lathe. Mount a rolling tip trimmingtool in a lathe tool mount. Place the end of the catheter onto thetrimming pin the distance necessary to achieve the specified trimlength. Turning the lathe at about 20 RPM, move the trimming tool intothe part until the tip is trimmed off. Stop the lathe and remove thepart and discard the trimmed piece.

Step C

1. Clean forming wires with 70:30 isopropyl alcohol/water.

2. Mount the catheter onto the forming wires until the distal tip isproperly aligned on the forming wire.

3. Arrange the catheter/forming wire assemblies onto the oven tray insuch a way that the soft tips are not in contact with anything otherthan the wire upon which they are mounted.

4. Place the tray into the forming oven at a desired temperature for adesired time.

5. After the parts have cooled, remove the forming wires and compare theshape to the specified shape template.

Step D

1. Slide a desired strain relief onto the proximal end of the catheterabout 3 inches (7.6 cm). Apply a desired adhesive around the end of thecatheter in a continuous bead, leaving the last 0.010 to 0.020 inches(0.25 to 0.051 cm) of catheter free of adhesive. Slide the catheter intothe hub, rotate the hub about 1 turn and align the wings of the hub inapproximately the same plane as the formed shape. Apply another smallbead of the specified adhesive to the bodystock immediately adjacent tothe hub, and slide the strain relief into the hub. Blot excess adhesivefrom the joint. Visually inspect the inside of the hub for excess glue.

FIGS. 6-12 relate to a diagnostic catheter of the present invention.Referring first to FIG. 6, there is indicated generally by numeral 110 adiagnostic catheter comprising the present invention. It includes anelongated tubular body 112 having a proximal end 114, a distal end 116and a lumen 118 extending therebetween. Affixed to the proximal end 114of the tubular body 112 is a molded plastic hub 120 having a Luerfitting 122 at its proximal end and flared wings 124 projecting radiallyfrom the diametrically opposed sides thereof to facilitate twisting ofthe catheter. An elastomeric sleeve 126 surrounds the proximal endportion of the tubular body 112 and functions as a strain relief member.The sleeve 126 is preferably roughened or knurled to facilitate grippingand rotation thereof using a three-finger catheter engagement. Thelength of the tubular body 112 will typically be 31/2 to 4 feet (1.1 to1.2 meters) in length and will have an outside diameter that isgenerally uniform over this length and will come in various sizes from,e.g., 3 Fr to 8 Fr.

Referring to the cross-sectional view of FIG. 7, it can be seen that thetubular body 112 is formed with an inner lubricious layer 128. With thismaterial for the inner layer 128, the surface defining the lumen 118 isinherently lubricious. The inner layer 128 preferably has a wallthickness in the range of from 0.001 to 0.008 inches (0.0025 to 0.0203cm) with 0.0025±0.0005 inches (0.0064±0.0127 cm) being preferred.

As can also be seen in the cross-sectional views of FIGS. 7 and 9, areinforcing means, in this case a braided sleeve of metal wires 130 isdisposed about the inner layer 128. As shown in FIG. 15, thecross-sectional view of the wires will generally be elliptical where thewires are braided and the filaments extend in a helix. The metallicreinforcing means 130 is described in more detail below.

Following placement of the reinforcing means, an outer layer 132 isdisposed onto the assembly. The outer layer may comprise a blend ofabout 90 weight percent polyetherester and about 10 weight percentpolybutylene terephthalate. As can be seen from the cross-sectionalviews of FIG. 9, the outer layer 132 may totally embed the reinforcingmeans 130. In certain embodiments, outer layer 132 substantially embedsreinforcing means 130, such that only minor portions of the reinforcingmeans 130 protrude from the outer layer 132. To provide a desired shapecharacteristic to the distal end portion of the diagnostic catheter, atubular stem member 134 may be thermally bonded to the distal endportion of the braided tubular body 112. As is best seen in FIG. 9, thebraided tubular body has its outer layer or jacket 132 ground to a bevelas at 136. By beveling the distal end portion 116 of the tubular body112, greater surface area is provided for effecting attachment of thestem member 134. In that the grinding operation used to create the bevelreduces the thickness of the outer jacket relative to the ends of thewires 130 comprising the braided sleeve, a band or ring 138 of anon-penetrable material may be used to surround the free ends of thebraid wires. Without such a band, the heating required to effect athermal bond between the tubular body 112 and the jacket 132 may causethe frayed ends of the braid to warp or bend to the point where they canpenetrate through the inner layer 128 into the lumen 118 or through thethickness of the tubular stem 134.

The stem member 134 may comprise, without limitation, polyetheresterelastomer, polybutylene terephthalate (PBT), or combinations thereof.Preferably, it will comprise a blend of about 90 weight percentpolyetherester and about 10 weight percent polybutylene terephthalate. Adesired pigment may be added as well. Additional materials that may beadded include titanium dioxide, bismuth subcarbonate and iodinecompounds.

Completing the catheter is a soft-tip member 140 which may be bonded tothe distal end portion of the stem member 134. A suitable durometer forthe soft-tip on the catheter is 30D -50D. That tip may be formed byinjection molding or welding the material onto the distal end of thestem member 134. Alternatively, if the catheter is not designed toinclude a stem member, the soft-tip 140 may be injection molded directlyonto a distal end portion of the braided tubular body 112 with animpenetrable ring 138 again being used to confine the braiding wire endsas the soft tip is being formed.

Using the above techniques, it has been possible to produce a 3 Fr O.D.catheter having a lumen with a diameter of 0.026 inches (0.066 cm) andwhich still possesses excellent torquing characteristics whereby thedistal end of the catheter follows a rotation of its proximal end.Moreover, even with such a relatively large diameter lumen in comparisonto its outer diameter, the catheter still has adequate column strengthallowing it to be advanced through the vascular system without kinkingor buckling. An 8 Fr diagnostic catheter constructed in accordance withthe present invention may have a lumen as large as 0.086 inches (0.218cm), again having the desirable properties expected by mostcardiologists as far as its ability to be manipulated through theapplication of longitudinal and rotational forces at the proximal endportion of the catheter.

The reinforcing layer of the present invention, in certain embodiments,may be completely or partially embedded in either the first or secondlayers. In certain embodiments, it will be partially covered by bothlayers.

FIG. 11 shows the outer layer of a distal portion of an alternativeembodiment of the present invention. The distal portion is made of apolyetherester/PBT blend having a hardness of 90D, and a tip made ofpolyetherester having a hardness of 30D. Intermediate the 90D and 30Dsections is an intermediate section made of polyetherester and having ahardness of 50D. In other embodiments, a hardness gradient will be used,so that the outer layer gradually becomes softer from the proximal tothe distal direction of the distal portion.

FIG. 12 shows a suitable braid pattern for the reinforcing braid. Here,a 32 strand, 1-over-1, paired construction is utilized with stainlesssteel wire. The preferred wire diameter may be about 0.0015 to 0.0035inches (0.0038 to 0.0089 cm), preferably about 0.0025 to 0.0030 inches(0.0064 to 0.0076 cm). Preferred braiding angles, as defined below, arebetween about 20-53 degrees, preferably about 30 -45 degrees. The braidillustrated in FIG. 12 would be made of a plurality of paired filaments,each pair extending in helix configuration along a center line of thebraid as a common axis, the braid provided by a first number of pairedfilaments having a common direction of winding but axially displacedrelative to each other pair and crossing a second number of pairedfilaments also axially disposed relative each other pair but having anopposite direction of winding. The paired wires, as shown, consist oftwo wires which make contact with one another along substantially theirentire length, preferably along their entire length. The reinforcingbraid will preferably be between about 90 and about 40 picks per inch.For a 6 Fr device, it will preferably be about 80 picks per inch, andfor devices between 7-10 Fr, it will preferably be about 52 picks perinch.

FIG. 13 shows an alternative braid pattern for the reinforcing means ofthe present invention. Here a 16 wire, two-over-two construction isutilized with stainless steel wire. The wire diameter may be the same asshown in FIG. 12. Preferred braiding angles are about 15-25 degrees.

FIG. 14 shows alternative angles that can be used in the presentinvention, namely 60°, 45°, and 30°, with the braid angle measured fromthe place perpendicular to the longitudinal axis of the catheter. Ingeneral, radiopacity increases as braid angles decrease.

It has been found that radiopacity can be predicted based on theeffective thickness of the metal braid content, and that preferredradiopacity properties are achieved with effective thickness of greaterthan about 0.002 inch (0.0051 cm), preferably between about 0.002 inch(0.0051 cm) and 0.0055 inch (0.0051 and 0.0140 cm), more preferablybetween 0.0029 and 0.0044 inch (0.0074 and 0.0112 cm).

The effective thickness can be calculated by dividing the totalcross-sectional wire area by the catheter outer diameter. The totalcross-sectional area of the wires can be determined in this embodimentwhere all wires have the same diameter and the filaments extend in ahelix by calculating the area for a single wire and multiplying theresult by the number of wires to yield a total cross-sectional wirearea. Then, the total cross-sectional wire area is divided by the outercatheter diameter.

With reference to FIG. 15, wires 130 are braided at an angle of 30° andhave diameters of 0.0030 inches (0.0076 cm). The cross-sectional area ofeach wire is shown as ellipses in FIG. 15, having a major diameter d₁ of0.00606 inches (0.0154 cm) and a minor diameter d₂ of 0.003 inches(0.0076 cm). The cross-sectional area of each wire is ##EQU1## The totalwire cross-sectional area for all 32 wires is 0.0004544 inches²(0.002932 cm²). This value is divided by the 0.105 inch (0.267 cm)diameter (D) of the catheter, to yield an effective thickness of 0.0043inch (0.0110 cm).

Polymeric materials that may be used in the present invention aredisclosed in U.S. patent application entitled "Intravascular Catheter",Ser. No. 08/647,606, filed concurrently herewith, and commonly assignedto the assignee of this application. Additional materials are disclosedin U.S. Pat. No. 5,403,292, and corresponding U.S. patent applicationentitled "Catheter Having Hydrophobic Properties", Ser. No. 08/343,153,filed Nov. 22, 1994, and both commonly assigned to the assignee of thisapplication.

U.S. Pat. No. 5,403,292 relates to a diagnostic intravascular catheterhaving an elongated tubular body with a proximal end, a distal end and alumen extending therebetween where the tubular body is formed with aninner layer consisting essentially of an unmodified polyamide polymer,preferably Nylon-12. The term "unmodified polyamide polymer" refers tothe fact that nothing is added to the polymer matrix that tends tosubstantially change its physical properties, such as copolymers,polymer blends, miscible polymers in relation to polyamide-based polymermatrices or polymer performance enhancers which would substantiallychange the physical properties of the polymer. For instance, the factthat a colorant or a radiopaque filler material is added is notconsidered to be a modification. Nylon-12 is hydrophobic meaning that itdoes not absorb moisture and swell. Surrounding this inner layer is areinforcing sleeve that extends from the proximal end of the tubularbody toward the distal end. The sleeve may comprise braided filamentsand may constrict the inner layer, creating microscopic bumps on thewall surface defining the lumen, effectively decreasing the contact areabetween an inserted guidewire and the wall surface. An outer layer,including a blend of a polyether block amide having a predetermineddiameter hardness in the range of from about 50 Shore D to 75 Shore Dand preferably a radiopaque filler material (BaSO₄), covers the innerlayer and the reinforcing sleeve and provides an outer diameter to thetubular body in the range of from 3-8 Fr. Preferably affixed to thedistal end of the tubular body member is a soft-tip member, which may bemolded from a blend of resins such that the soft tip exhibits a hardnessthat is less than about 45 Shore D. The intravascular catheter may alsoincorporate a non-braided tubular stem member that is interposed betweenand bonded to both the tubular body and the soft-tip member. The stemmember itself preferably comprises a single layer of a copolymer ofpolyamide and PEBA whose Shore hardness is in the range of from 25D to72D. It may have a uniform or tapered outer diameter.

The following Table I provides a list of polymers suitable for a firstlayer of the present invention and provides certain properties of thesepolymers, as found in Polymer Structure, Properties and Applications, R.D. Deanin, Cahners Books (1972).

The following Tables II and III provide properties of certainpolyetheresters suitable for a second layer of the present invention.

The following Table IV provides certain properties of polybutyleneterephthalate suitable for a second layer of the present invention.

Those skilled in the art will also appreciate that the intravascularcatheter in accordance with the present invention can be manufactured tohave a variety of different distal end shaped configurations to suit thedesires of different cardiologists. In certain embodiments, the presentinvention can be used in such diverse catheter applications asneurological catheters, angioplasty catheters, stent deployment devices,and the like.

Various modifications and changes in detail may be made to theabove-described embodiments and examples without departing from thespirit and scope of the invention. It is therefore intended that allsuch matter as described in the foregoing description and shown in theattached drawings be considered as illustrative only and not limiting.

                  TABLE I                                                         ______________________________________                                                      Steel on Polymer                                                                        Polymer on Polymer                                    Polymer         Static Kinetic  Static                                                                              Kinetic                                 ______________________________________                                        PTFE ("Teflon") 0.10   0.05     0.04  0.04                                    (polytetrafluoroethylene)                                                     PTFE-HFP copolymer (FEP                                                                       0.25   0.18     --    --                                      "Teflon") (Tetrafluoroethylene/                                               hexafluoropropylene)                                                          Polyethylene (low density)                                                                    0.27   0.26     0.33  0.33                                    Polyethylene (high density)                                                                   0.18   0.08-0.12                                                                              0.12  0.11                                    Acetal resin ("Delrin")                                                                       0.14   0.13     --    --                                      Polyvinylidene fluoride                                                                       0.33   0.25     --    --                                      Polycarbonate   0.60   0.53     --    --                                      PET ("Mylar")   0.29   0.28     0.27* 0.20*                                   (polyethylene terephthalate)                                                  Nylon           0.37   0.34     0.42* 0.35*                                   (polyhexamethylene adipamide)                                                 PFCE ("Kel-F")  0.45*  0.33*    0.43* 0.32*                                   (polytrifluorochloroethylene)                                                 PVC (polyvinyl chloride)                                                                      0.45*  0.40*    0.50* 0.40*                                   PVDC            0.68*  0.45*    0.90* 0.52*                                   (polyvinylidene chloride)                                                     ______________________________________                                         *"Stickslip" (intermittent motion).                                      

                                      TABLE II                                    __________________________________________________________________________    Property/Test Method                                                                      Grade 1                                                                            Grade 2                                                                            Grade 3                                                                            Grade 4                                                                            Grade 5                                       __________________________________________________________________________    Relative Viscosity/                                                                       3.45 ± 0.2                                                                      2.90 ± 0.2                                                                      3.20 ± 0.2                                                                      3.40 ± 0.2                                                                      2.90 ± 0.2                                 DIN 50.049-3.1.B                                                              Moisture Content/ASTM                                                                     <0.025                                                                             <0.025                                                                             <0.025                                                                             <0.025                                                                             <0.025                                        D4019 (%)                                                                     Melting Point/ASTM                                                                        383  365  395  415  430                                           D2217 (° F.)                                                           Hardness/ASTM                                                                             38   45   55   63   74                                            D2240 (Shore D)                                                               Melt Flow Index/ASTM                                                                      25   40   10   7    4                                             D1238 (g/10 min.)                                                             Tensile Modulus/ASTM                                                                      8,700                                                                              16,000                                                                             32,000                                                                             54,000                                                                             130,000                                       D638 (psi)                                                                    Tensile Strength/ASTM                                                                     2,470                                                                              3,050                                                                              4,640                                                                              5,800                                                                              6,520                                         D638 (psi)                                                                    Elongation at Break/ASTM                                                                  700  800  650  600  360                                           D638 (%)                                                                      Flexural Modulus/ASTM                                                                     7,980                                                                              15,000                                                                             29,000                                                                             48,500                                                                             117,000                                       D790 (%)                                                                      __________________________________________________________________________

                  TABLE III                                                       ______________________________________                                        Property/Test Method                                                          ______________________________________                                        Melt Flow Rate, 190° C. at 2.16 kg/ASTM D-1238                                                 5.0 ± 1.5                                          (g/10 min.)                                                                   Melting Point/ASTM D-3418                                                                             170 ± 3                                            (° C.)                                                                 Specific Gravity        1.07 ± 0.02                                        Hardness/ASTM D2240      30                                                   (Durometer)                                                                   Flex Modulus/ASTM D790 at 73° F.                                                               4000                                                  (psi)                                                                         Tensile Strength at Break/ASTM D638                                                                   3800                                                  (psi)                                                                         Elongation at Break/ASTM D638                                                                          700                                                  (%)                                                                           ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                        Property/Test Method                                                          ______________________________________                                        Viscosity Number/ISO 1628-5 (cm.sup.3 /g)                                                            165 ± 7                                             Volume Melt Flow Rate/ISO 1133                                                                       10 ± 3                                              (cm.sup.3 /10 min.)                                                           Moisture Content/ASTM D4019 (wt. - %)                                                                  ≦0.05                                         Density at 23° C./ISO 1183 (g/cm.sup.3)                                                       1.31 ± 0.03                                         Melting Range/DSC (° C.)                                                                      221-226                                                Tensile Strength at Yield/ISO 527 (N/mm.sup.2)                                                       ≧50                                             Elongation at Yield/ISO 527 (%)                                                                       ≧3                                             Tensile Strength at Break/ISO 527 (N/mm.sup.2)                                                       ≧30                                             Elongation at Break/ISO 527 (%)                                                                      ≧100                                            Modulus of Elasticity/ISO 527 (N/mm.sup.2)                                                           ≧2200                                           ______________________________________                                    

What is claimed is:
 1. A catheter comprising an elongate tubular body having a proximal portion, a distal portion, and a lumen extending therebetween, the tubular body comprising:(a) a polymeric material; and (b) a metallic reinforcing braid comprising elongate filaments having substantially circular cross-sections, the braid having greater than 40 picks per inch and an effective thickness, calculated as total cross-sectional wire area divided by catheter outer diameter, of greater than 0.002 inches (0.0051 cm).
 2. The catheter of claim 1 wherein the metallic reinforcing braid has an effective thickness of between about 0.0029 and about 0.0044 inches.
 3. A catheter comprising an elongate tubular body having a proximal portion, a distal portion and a lumen extending therebetween, the tubular body comprising:(a) polymeric material comprising substantially no radiopaque filler; and (b) a metallic reinforcing braid; wherein the combination of polymeric material comprising substantially no radiopaque filler and metallic braid has an amount of radiopacity which is greater than or equal to the amount of radiopacity which would result from a catheter without metallic reinforcing consisting of polymeric material loaded with 20% barium sulfate.
 4. The catheter of claim 3 wherein the combination of polymeric material comprising substantially no radiopaque filler and metallic braid has an amount of radiopacity which is greater than or equal to the amount of radiopacity which would result from a catheter without metallic reinforcing consisting of polymeric material loaded with 30% barium sulfate.
 5. The catheter of claim 4 wherein the combination of polymeric material comprising substantially no radiopaque filler and metallic braid has an amount of radiopacity which is greater than or equal to the amount of radiopacity which would result from a catheter without metallic reinforcing consisting of polymeric material loaded with 40% barium sulfate.
 6. An intravascular catheter comprising an elongate tubular body having a proximal portion, a distal portion and a lumen extending therebetween, the tubular body comprising:(a) a first layer defining the lumen, the first layer comprising polymeric material having a kinetic coefficient of friction (steel on polymer) of less than about 0.50; (b) a second layer disposed about the first layer, the second layer comprising polymeric material selected from polyetherester elastomer, polybutylene terephthalate, and combinations thereof; and (c) a metallic reinforcing braid comprising elongate filaments having substantially circular cross-sections, the braid having greater than 40 picks per inch and an effective thickness, calculated as total cross-sectional wire area divided by catheter outer diameter, of greater than 0.002 inches (0.0051 cm).
 7. The intravascular catheter of claim 6 wherein the first layer comprises a polymer selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, and polyamide.
 8. The intravascular catheter of claim 6 wherein the first layer comprises a polymer having a kinetic coefficient of friction (steel on polymer) less than about 0.10.
 9. The intravascular catheter of claim 8 wherein the first layer consists essentially of polytetrafluoroethylene.
 10. The intravascular catheter of claim 6 wherein the second layer has a durometer of from about 30D-90D.
 11. The intravascular catheter of claim 6 wherein the second layer comprises polyetherester blended with polybutylene terephthalate.
 12. The intravascular catheter of claim 11 wherein the second layer comprises about 10-94 weight percent polybutylene terephthalate.
 13. The intravascular catheter of claim 12 wherein the second layer comprises about 8-12 weight percent polyetherester and about 88-92 weight percent polybutylene terephthalate.
 14. The intravascular catheter of claim 6 wherein the metallic reinforcing braid is totally embedded between the first layer and the second layer.
 15. The intravascular catheter of claim 6 wherein the metallic reinforcing braid is substantially embedded in the second layer.
 16. The intravascular catheter of claim 6 wherein the metallic reinforcing braid extends from the proximal portion of the tubular body toward the distal portion of the tubular body.
 17. The intravascular catheter of claim 16 wherein the metallic braid comprises metal filaments braided in a one-over-one pattern.
 18. The intravascular catheter of claim 16 wherein the metallic braid comprises metal filaments braided in a two-over-two configuration.
 19. The intravascular catheter of claim 16 wherein the metallic braid comprises filaments formed of a metal selected from stainless steel and ELGILOY nickel-cobalt alloy. 